The present invention relates generally to electrical connectors. More particularly, the invention relates to a feed-through connector and method of making the same, for the transmission of electrical signals across a boundary such as a fluid boundary and a method of installing and holding the connectors into an outlet.
Feed-through connectors find many applications where an electrical signal must be conveyed across a boundary, through a bulkhead or chassis wall, etc. Where the boundary serves as a fluid barrier, such as in the case of an oil-containing engine or transmission casing, the connector should be made as leakproof as possible. This is especially true when the fluid system is pressurized.
In the past it has been recognized that when wires are used to convey a signal from one side of the fluid barrier to the other, leakage will often occur at the aperture through which the wire is passed. In some instances, the wire will act as a wick, tending to duct fluid through the aperture causing leaks. It has heretofore been quite difficult to prevent such leaks using conventional sealing components. Sealing components, such as caulking material, tends to loose its resiliency over time, allowing leaks to occur.
Accordingly, in many leak-prone applications a solder-type connector is used. While less apt to leak, such connectors are expensive to use in manufacturing operations, since labor is required to solder wires to both ends of the connector. Also, solder-type connectors tend to be rather large and bulky, since they must be of a certain size in order to accommodate the soldering of a wire lead. Furthermore, solder-type connectors are more prone to failure, since each solder joint represents a potential failure point. By way of example, a 14 wire harness would require 28 solder connections in order to conduct all signals through a boundary wall or bulkhead. In addition to be potential failure points due to poor soldering or breakage, multiple solder connections can also result in shorted wires due to solder bridging between adjacent connector pins.
Another type of connector sometimes used to transmit signals across a boundary is the conventional plug and jack arrangement in which the plug communicates with one side of the boundary and the jack communicates with the other side. Although suitable for some applications, the plug and jack connector may not be suitable in applications where there is a lot of vibration. Also, being separable units, plug and jack connectors rely on physical contact between two conductor surfaces (plug and jack surfaces). When the surfaces become corroded or oxidized, signal flow is impeded.
The present invention provides a connector apparatus and method of low cost which is well-suited to mass production applications. The connector can be used to pass signals through fluid barriers, bulkheads, engine and transmission casings, and the like without the need for any soldered connections. In addition, the connector does not require separate physical plug and jack components, but instead utilizes a continuous wire conductor to convey the signal from one side of the fluid barrier to the other. Thus the connector of the invention will not degrade signal performance due to corrosion or oxidation and it will not become intermittent when subjected to vibration.
In accordance with the inventive method, a leakproof feed-through connector is formed using one or more wires having a center conductor and having an outer concentric sheath. According to the method, a portion of the sheath around a medial section of the wire is removed to expose an annular surface of the conductor and to define an adjacent surface of the sheath. The wire is then placed in a supporting structure having a recess. The wire is placed so that the exposed annular surface is disposed within the recess. The recess is substantially filled with a sealing material so that the sealing material contacts both the exposed annular surface and the adjacent surface of the sheath. A sealing material is caused to be secured in place in contact with the annular surface and in contact with the adjacent surface of the sheath. In this way, the annular surface, the adjacent surface of the sheath, and the sealing material all coact to define a serpentine boundary which inhibits fluid leakage along the wire. The leakproof feed-through connector is then secured to a circuit board with a biasing spring located between the circuit board and the leakproof connector in order to position the connector with respect to the circuit board. The attachment of the connector to the circuit board and the biasing of the connector with respect to the circuit board allows the installation of the connector into a blind aperture within a housing. Using the circuit board as a guide, the connector can be positioned within the blind aperture and the securing of the circuit board to the housing will cause the biasing spring to deflect and urge the connector into the aperture to complete the assembly.
Thus the invention provides a leakproof, feed-through connector for conducting an electrical signal from one side of a fluid boundary to another, the fluid boundary having an aperture into which the feed-through connector is inserted. The connector comprises a plug portion having an outer surface which conforms to the shape of the aperture, for insertion in and sealing the aperture. A recess forming portion defining a recess is integrated with the plug portion. A wire supporting portion is also integrated with the plug portion. At least one wire for conducting an electrical signal is disposed in the wire supporting portion. The wire has a center conductor and an outer concentric sheath. A portion of the sheath around a medial section of the wire is removed to expose an annular surface of the conductor and to define an adjacent surface. The wire is disposed in the wire supporting portion so that the annular surface and the adjacent surface of the sheath are both disposed within the recess. A sealing material substantially fills the recess so that it contacts the annular surface and the adjacent surface. In this way the sealing material, the annular surface and the adjacent surface all coact to define a serpentine boundary which inhibits fluid leakage from one side of the fluid boundary to the other. The connector is attached to a circuit board which is used as a guide to direct the connector into a blind aperture in a housing. Once the circuit board is secured to the housing, a biasing spring disposed between the circuit board and the housing operates to hold the connector within the blind aperture.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings.